Damage tolerance reliability analysis of automotive spot-welded joints |
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Authors: | Sankaran Mahadevan Kan Ni |
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Affiliation: | Department of Civil and Environmental Engineering, Vanderbilt University, Box 1831-B, Nashville, TN 37235, USA |
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Abstract: | This paper develops a damage tolerance reliability analysis methodology for automotive spot-welded joints under multi-axial and variable amplitude loading history. The total fatigue life of a spot weld is divided into two parts, crack initiation and crack propagation. The multi-axial loading history is obtained from transient response finite element analysis of a vehicle model. A three-dimensional finite element model of a simplified joint with four spot welds is developed for static stress/strain analysis. A probabilistic Miner's rule is combined with a randomized strain-life curve family and the stress/strain analysis result to develop a strain-based probabilistic fatigue crack initiation life prediction for spot welds. Afterwards, the fatigue crack inside the base material sheet is modeled as a surface crack. Then a probabilistic crack growth model is combined with the stress analysis result to develop a probabilistic fatigue crack growth life prediction for spot welds. Both methods are implemented with MSC/NASTRAN and MSC/FATIGUE software, and are useful for reliability assessment of automotive spot-welded joints against fatigue and fracture. |
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Keywords: | Spot weld joint Fatigue Fracture Probabilistic analysis Strain life Crack growth Multi axial loading Variable amplitude loading Finite element modeling |
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